Impeller and blower

ABSTRACT

A blower includes an impeller rotatable about a central axis and a motor driving the impeller. The impeller includes a first impeller, and a second impeller connected to the first impeller. The first impeller includes a base and first blades arranged in a circumferential direction. The base includes a cup portion of which an axially upper end is closed and a flange extending radially outward from an axially lower end of the cup portion. The second impeller includes a shroud with an annular or substantially annular shape about the central axis and axially opposes an upper surface of the flange, and second blades arranged in the circumferential direction. Each first blade protrudes axially upward from the flange. Each second blade protrudes axially downward from the shroud.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a U.S. national stage of PCT Application No. PCT/JP2018/019296,filed on May 18, 2018, and priority under 35 U.S.C. § 119(a) and 35U.S.C. § 365(b) is claimed from Japanese Application No. 2017-129868,filed Jun. 30, 2017; the entire disclosures of each which are herebyincorporated herein by reference.

1. FIELD OF THE INVENTION

The present disclosure relates to an impeller and a blower.

2. BACKGROUND

In the related art, a centrifugal fan is known, which radially outwardsends out air taken in the fan by a rotation of an impeller. Forexample, in related art, a centrifugal blower fan is known, in which amotor and an impeller are accommodated inside a casing. The impellerintegrally includes a plurality of blades, an annular band which isdefined by joining one end side of the plurality of blades into one, anda flat donut-shaped disk which is defined by joining the other side ofthe plurality of blades into one. A claw located on the disk side of theimpeller is inserted into a notch which is provided in a flange of abottomed cylindrical back yoke. Accordingly, the impeller is fixed tothe back yoke constituting a rotor of the motor.

However, in the centrifugal blower fan of the related art, a portion ofthe air taken into the impeller may escape to the outside from a gapbetween the disk and the back yoke on the one end side of the pluralityof blades. In this case, it is not possible to radially outward send outthe air taken into the impeller efficiently.

SUMMARY

An example embodiment of an impeller of the present disclosure isrotatable about a central axis extending in an axial direction. Theimpeller includes a first impeller, and a second impeller connected tothe first impeller. The first impeller includes a base and a pluralityof first blades arranged in a circumferential direction. The baseincludes a cup portion of which an axially upper end is closed and aflange extending radially outward from an axially lower end of the cupportion. The second impeller includes a shroud and a plurality of secondblades. The shroud has an annular or substantially annular shape aboutthe central axis and opposes an upper surface of the flange in an axialdirection. The second blades are arranged in the circumferentialdirection. Each of the first blades protrudes axially upward from theflange. Each of the second blades protrudes axially downward from theshroud. In the circumferential direction, at least one second blade islocated between the first blades adjacent to each other.

An example embodiment of a blower of the present disclosure includes theimpeller which is rotatable about the central axis and a motor whichdrives the impeller.

The above and other elements, features, steps, characteristics andadvantages of the present disclosure will become more apparent from thefollowing detailed description of the example embodiments with referenceto the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a configuration example ofa centrifugal fan according to an example embodiment of the presentdisclosure.

FIG. 2 is a perspective view of an impeller according to an exampleembodiment of the present disclosure when viewed from an axially upperside.

FIG. 3 is an exploded perspective view of the impeller.

FIG. 4 is an enlarged perspective view of a second impeller according toan example embodiment of the present disclosure when viewed from anaxially lower side.

FIG. 5 is a top view of the impeller.

FIG. 6 is a cross-sectional view illustrating a configuration example ofa fixing portion according to an example embodiment of the presentdisclosure.

FIG. 7 is a cross-sectional view illustrating another configurationexample of the fixing portion according to an example embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Hereinafter, example embodiments of the present disclosure will bedescribed with reference to the drawings.

In the present specification, in an impeller 100 and a centrifugal fan200, a direction parallel to a central axis CA is referred to as an“axial direction”. Furthermore, in the axial direction, a direction froma first impeller 1 to a second impeller 2 is referred to as an “axiallyupper side”, and a direction from the second impeller 2 to the firstimpeller 1 is referred to as an “axially lower side”. In each component,an end on the axially upper side is referred to as an “axially upperend”, and an end on the axially lower side is referred to as an “axiallylower end”. Further, in surfaces of each component, a surface facing theaxially upper side is referred to as an “upper surface”, and a surfacefacing the axially lower side is referred to as a “lower surface”.

A direction orthogonal to the central axis CA is referred to as a“radial direction”, and a rotation direction about the central axis CAis referred to as a “circumferential direction”. Further, in the radialdirection, a direction toward the central axis CA is referred to as a“radially inner side”, and a direction away from the central axis CA isreferred to as a “radially outer side”. In each component, an end on theradially inner side is referred to as a “radially inner end”, and an endon the radially outer side is referred to as a “radially outer end”. Inaddition, in side surfaces of each component, a side surface facing theradially inner side is referred to as an “inner side surface”, a sidesurface facing the radially outer side is referred to as an “outer sidesurface”, and a side surface facing the circumferential direction isreferred to as a “circumferential side surface”.

Moreover, the above-described designations with respect to thedirections and the surfaces do not indicate a positional relationshipand a direction when incorporated in an actual device.

FIG. 1 is a cross-sectional view illustrating a configuration example ofthe centrifugal fan 200. Moreover, in FIG. 1, the centrifugal fan 200 iscut along a cut surface including the central axis CA. As illustrated inFIG. 1, the centrifugal fan 200 is a blower including the impeller 100and a motor 110 which rotationally drives the impeller 100. The impeller100 is attached to a rotor (not illustrated) of the motor 110, and isrotatable about the central axis CA extending vertically, together withthe rotor.

FIG. 2 is a perspective view of the impeller 100 when viewed from theaxially upper side. FIG. 3 is an exploded perspective view of theimpeller 100. The impeller 100 includes the first impeller 1 and thesecond impeller 2 which is connected to the first impeller 1. Accordingto this configuration, the first impeller 1 and the second impeller 2are assembled to each other in the vertical direction, and thus, theimpeller 100 is able to be obtained.

The first impeller 1 has a base 11 and a plurality of first blades 12which are arranged in the circumferential direction. The base 11 has acup portion 111 extending in the axial direction and an annular flange112. An axially upper end of the cup portion 111 is closed. An axiallylower end of the cup portion 111 is open, and an upper portion of themotor 110 is accommodated in the cup portion 111 through an opening ofthe axially lower end. The flange 112 extends radially outward from theaxially lower end of the cup portion 111.

A first groove 11 a and a through-hole 11 b are provided in the base 11.In other words, the base 11 further includes the first groove 11 a andthe through-hole 11 b. The first groove 11 a is provided on an uppersurface of the flange 112 of the base 11. The first groove 11 a isrecessed axially downward between the first blades 12 adjacent to eachother in the circumferential direction. The first groove 11 a extends ina direction including at least a radial component of the radialcomponent and a circumferential component. The through-hole 11 b isprovided in a radially inner end of the first groove 11 a and penetratesthe base 11 in the axial direction.

If the impeller 100 rotates, air flows in from an annular shroud 21.That is, the air flows in from the radially inner side rather than aradially inner peripheral edge 21 b of the shroud 21. Each of the firstblades 12 protrudes axially upward from an upper surface of at leastflange 112 of the base 11. Therefore, a gap is not defined between thefirst blades 12 and the flange 112. Accordingly, the air does not escapein the circumferential direction through the gap. Therefore, when theimpeller 100 rotates, the first blades 12 are able to efficiently sendout the air to the radially outer side of the impeller 100. The firstblade 12 extends in a direction including at least a radial component ofthe radial component and a circumferential component.

FIG. 4 is an enlarged perspective view of the second impeller 2 whenviewed from the axially lower side. The second impeller 2 has a shroud21 and a plurality of second blades 22 which are arranged in thecircumferential direction.

The shroud 21 has an annular or substantially annular shape about thecentral axis CA and faces the base 11 of the first impeller 1 in theaxial direction. In the example embodiment of the present disclosure,the shroud 21 faces the upper surface of the flange 112 of the base 11in the axial direction. A second groove 21 a is provided on a lowersurface of the shroud 21. In other words, the shroud 21 has the secondgroove 21 a. The second groove 21 a is recessed axially upward betweenthe second blades 22 adjacent to each other in the circumferentialdirection. The second groove 21 a extends in a direction including atleast a radial component of the radial component and a circumferentialcomponent.

The second groove 21 a extends along the first blade 12 when viewed inthe axial direction. Therefore, in a case where the second impeller 2 isconnected to the first impeller 1, an axially upper end of the firstblade 12 is located in the second groove 21 a. Thereby, even in a casewhere a gap is defined between the first blade 12 and the shroud 21, itis possible to prevent the air from leaking from a portion between thefirst blade 12 and the shroud 21. Accordingly, when the impeller 100rotates, it is possible to suppress a decrease in efficiency which theair is sent to the radially outer side of the impeller 100 by the firstblades 12.

Each of the second blades 22 protrudes axially downward from the shroud21. Therefore, a gap is not defined between the second blades 22 and theshroud 21. Accordingly, when the impeller 100 rotates, the second blades22 are able to efficiently send out the air to the radially outer sideof the impeller 100.

The second blade 22 extends in a direction including at least a radialcomponent of the radial component and a circumferential component. FIG.5 is a top view of the impeller 100. In addition, in FIG. 5, the shroud21 is indicated by broken lines. When viewed in the axial direction, asillustrated in FIG. 5, each of the second blades 22 extends along thefirst groove 11 a of the base 11. Therefore, in the case where thesecond impeller 2 is connected to the first impeller 1, an axially lowerend of the second blade 22 is located in the first groove 11 a. Thereby,even in the case where a gap is defined between the second blade 22 andthe base 11, it is possible to prevent the air from leaking from aportion between the second blade 22 and the base 11. Accordingly, whenthe impeller 100 rotates, it is possible to suppress a decrease inefficiency which the air is sent to the radially outer side of theimpeller 100 by the second blades 22.

In the example embodiment of the present disclosure, the axially lowerends of all the second blade portions 22 are located in the respectivefirst grooves 11 a. However, the present disclosure is not limited tothis example, and the axially lower ends of some of the second blades 22may be located in the first grooves 11 a. In other words, in thecircumferential direction, the axially lower end of at least one secondblade 22 may be located in the first groove 11 a.

In the case where the second impeller 2 is connected to the firstimpeller 1, in the circumferential direction, the second blade 22 islocated between the first blades 12 adjacent to each other. That is, thesecond blade 22 is located between the first blades 12 adjacent to eachother in the circumferential direction. Thereby, blowing efficiency ofimpeller 100 is further improved.

In the example embodiment of the present disclosure, all the secondblades 22 are located between the first blades 12 adjacent to eachother. However, the present disclosure is not limited to this example,and some of the second blades 22 may be located between the first blades12 adjacent to each other. In other words, in the circumferentialdirection, at least one second blade 22 may be located between the firstblades 12 adjacent to each other.

When viewed in the axial direction, as illustrated in FIG. 5, a radiallyinner end of the second blade 22 is located radially outside a radiallyinner end of the first blade 12. Accordingly, it is possible to preventa gap between the first blade 12 and the second blade 22 from beingnarrowed which occurs because the first blade 12 and the second blade 22are adjacent to each other at the radially inner end. Accordingly, aflow of the air flowing through a portion between the first blades 12adjacent to each other is not able to be easily hindered.

Moreover, when viewed in the axial direction, as illustrated in FIG. 5,the radially inner end of the second blade 22 is located radiallyoutside a radially outer end of the cup portion 111. Accordingly, whenthe second impeller 2 is connected to the first impeller 1, it ispossible prevent the second blades 22 from abutting on the cup portion111. Therefore, a connection operation of the first impeller 1 and thesecond impeller 2 is easily performed.

As illustrated in FIG. 5, when viewed in the axial direction, a lengthin an extension direction of the second blade 22 is shorter than alength in an extension direction of the first blade 12. Accordingly,when the second impeller 2 is connected to the first impeller 1, thesecond blade 22 does not easily abut on the cup portion 111. Therefore,a connection operation of the first impeller 1 and the second impeller 2is easily performed.

A fixing portion 221 is provided in the axially lower end of the secondblade 22. In other words, the second blade 22 has the fixing portion221. The fixing portion 221 extends axially downward from the secondblade 22 and is fixed to the base 11 through the through-hole 11 b.Accordingly, the second impeller 2 is able to be easily connected to thefirst impeller 1. Moreover, in the example embodiment the presentdisclosure, the fixing portion 221 is provided in all the second bladeportions 22. However, the present disclosure is not limited to thisexample, and the fixing portion 221 may be provided in some secondblades 22. In other words, the fixing portion 221 may be provided in atleast one second blade 22 in the circumferential direction.

The impeller 100 further has a filler 3. The filler 3 is provided insidethe through-hole 11 b through which the fixing portion 221 passes. Inthe through-hole 11 b, the filler 3A fills a portion between the fixingportion 221 and an radially inner side surface of the through-hole 11 b.According to the filling of the filler 3, it is possible to prevent theair flowing between the first blades 12 from leaking in the axialdirection through the through-hole 11 b.

FIG. 6 is a cross-sectional view illustrating a configuration example ofthe fixing portion 221. As illustrated in FIG. 6, the fixing portion 221has a claw 221 a. After the fixing portion 221 passes through thethrough-hole 11 b, the claw 221 a is hooked to a lower surface of thebase 11. Accordingly, when the impeller 100 is assembled, the secondimpeller 2 is able to be easily connected to the first impeller 1.Moreover, in the example embodiment of the present disclosure, the claw221 a is provided in all the second blade portions 22. However, thepresent disclosure is not limited to this example, and the claw 221 amay be provided in some second blades 22. In other words, the claw 221 amay be provided in at least one second blade 22 in the circumferentialdirection.

In a case where the claw 221 a is hooked to the lower surface of thebase 11, as illustrated in FIG. 6, an upper surface of the claw 221 a isin contact with the lower surface of the base 11. Further, the axiallylower end of the second blade 22 inserted into the first groove 11 afaces a bottom surface of the first groove 11 a with a gap between thebottom surface of the first groove 11 a and the axially lower end of thesecond blade 22. That is, when the second impeller 2 is connected to thefirst impeller 1, first, the upper surface of the claw 221 a and thelower surface of the base 11 come into contact with each other.Accordingly, it is possible to prevent a gap from being generatedbetween the upper surface of the claw 221 a and the lower surface of thebase 11. Therefore, it is possible to increase connection strengthbetween the first impeller 1 and the second impeller 2.

Moreover, the claw 221 a is covered with the filler 3 outside thethrough-hole 11 b. Accordingly, at least a portion of the claw 221 a isable to be fixed to the base 11 by the filler 3, and thus, it ispossible to further increase the connection strength between the firstimpeller 1 and the second impeller 2. In addition, in the exampleembodiment of the present disclosure, the claw 221 a is covered with thefiller 3 provided in the through-hole 11 b. However, the presentdisclosure is not limited to this example, and the claw 221 a may becovered with a member different from the filler 3.

The claw 221 a is provided on an axially lower side of a radially oneend of at least one second blade 22. Accordingly, when the secondimpeller 2 is molded using a metal mold, it is possible to extract themetal mold in the axial direction. Accordingly, the impeller 100 iseasily manufactured. In the example embodiment of the presentdisclosure, the claw 221 a is provided on an axially lower side of theradially inner end of the second blade 22. Accordingly, compared to acase where the claw 221 a is provided on an axially lower side of aradially outer end of the second blade 22, it is possible to prevent theclaw 221 a from jumping out to the radially outer side of the base 11.When the impeller 100 is assembled, the claw 221 a does not easilyinterfere with other members, which facilitates an assembling operation.Moreover, the claw 221 a is not limited to the example of the exampleembodiment of the present disclosure, and the claw 221 a may be providedon the axially lower side of the radially outer end of the second blade22.

The claw 221 a is located radially inside the radially inner peripheraledge 21 b of the shroud 21. When viewed in the axial direction, the claw221 a extends from the radially inner end of the second blade 22 to thecentral axis CA side in the direction in which the second blade 22extends. Accordingly, when the second impeller 2 is molded using themetal mold, it is possible to extract the metal mold in the axialdirection. Accordingly, the impeller 100 is easily manufactured.Moreover, when the second impeller 2 is connected to the first impeller1, the first blade 12 adjacent to at least one second blade 22 does noteasily come into contact with the claw 221 a.

FIG. 7 is a cross-sectional view illustrating another configurationexample of the fixing portion 221. As illustrated in FIG. 7, the fixingportion 221 has a thermal deformation portion 221 b. A portion of thefixing portion 221 is thermally deformed, and thus, the thermaldeformation portion 221 b is defined. The thermal deformation portion221 b is in contact with the lower surface of the base 11. Morespecifically, for example, after the fixing portion 221 defined using athermally deformable material such as a thermoplastic resin passesthrough the through-hole 11 b, a distal end of the fixing portion 221protruding outside the through-hole 11 b is welded to the lower surfaceof the base 11. This welded portion becomes the thermal deformationportion 221 b. Accordingly, when the impeller 100 is assembled, thesecond impeller 2 is able to be easily connected to the first impeller1.

According to the above-described example embodiment of the presentdisclosure, the centrifugal fan 200 includes the impeller 100 which isrotatable about the central axis CA, and the motor 110 which drives theimpeller 100.

According to the above-described example embodiment of the presentdisclosure, the impeller 100 which is rotatable about the central axisCA extending in the vertical direction includes the first impeller 1 andthe second impeller 2 which is connected to the first impeller 1. Thefirst impeller 1 has the base 11 and a plurality of first blades 12which are arranged in the circumferential direction. The base 11 has thecup portion 111 of which the axially upper end is closed and the flange112 which extends radially outward from the axially lower end of the cupportion 111. The second impeller 2 has the shroud 21 which has anannular or substantially annular shape about the central axis CA andfaces the upper surface of the flange 112 in the axial direction, andthe plurality of second blades 22 which are arranged in thecircumferential direction. Each first blade 12 protrudes axially upwardfrom the flange 112. Each second blade 22 protrudes axially downwardfrom the shroud 21. In the circumferential direction, At least onesecond blade 22 is located between the first blades 12 adjacent to eachother.

Accordingly, since, in the circumferential direction, at least onesecond blade 22 is located between the first blades 12 adjacent to eachother, when the impeller 100 rotates, it is possible to efficiently sendout the air radially outward from a portion radially inside the radiallyinner peripheral edge 21 b of the annular shroud 21 via a portionbetween the shroud 21 and the base 11. In addition, the first blade 12protrudes from the flange 112 facing the shroud 21. Thereby, a gap isnot able to be defined between the first blade 12 and the flange 112.Accordingly, when the impeller 100 rotates, the air does not escape inthe circumferential direction through the gap. Moreover, the secondblade 22 protrudes from the shroud 21. Thereby, a gap is not able to bedefined between the second blade 22 and the shroud 21. Accordingly, thefirst blades 12 and the second blades 22 are able to efficiently sendout the air radially outward. Moreover, the impeller 100 is anothermember including the first impeller 1 and the second impeller 2.Accordingly, there is a possibility that the air may leak from aconnection portion between the first blade 12 and the second blade 22.However, the gap is not able to be defined between the first blade 12and the flange 112. Accordingly, even when the air leaks from theconnection portion, it is possible to suppress an influence on a flow ofthe air sent out to the radially outer side of the impeller 100.Therefore, it is possible to improve the blowing efficiency of theimpeller 100.

The impeller 100 includes the first impeller 1 and the second impeller2. Accordingly, even when the base 11 of the first impeller 1 isconfigured to face the shroud 21 of the second impeller 2 in the axialdirection, it is possible to mold the first impeller 1 and the secondimpeller 2 by extracting the metal molds in the vertical direction,respectively.

According to the above-described example embodiment of the presentdisclosure, the base 11 has the first groove 11 a which is recessedaxially downward. The first groove 11 a is provided between the firstblades 12 adjacent to each other and extends in the direction in whichat least one second blade 22 extends. The axially lower end of at leastone second blade 22 is located in the first groove 11 a.

Accordingly, even in the case where a gap is defined between at leastone second blade 22 and the base 11, it is possible to prevent the airfrom leaking from a portion between the second blade 22 and the base 11.Thereby, it is possible to suppress the decrease in efficiency which theair is sent to the radially outer side of the impeller 100 by at leastone second blade 22.

According to the above-described example embodiment of the presentdisclosure, the base 11 has the through-hole 11 b which penetrates thebase 11 in the axial direction. At least one second blade 22 has thefixing portion 221 extending in the axial direction. The fixing portion221 is fixed to the base 11 through the through-hole 11 b.

Accordingly, the fixing portion 221 is fixed to the base 11, and thus,it is possible to easily connect the first impeller 1 and the secondimpeller 2, which are combined in the vertical direction, to each other.

According to the above-described example embodiment of the presentdisclosure, the fixing portion 221 may have the thermal deformationportion 221 b in which a portion of the fixing portion 221 is thermallydeformed. The thermal deformation portion 221 b is in contact with thelower surface of the base 11.

Therefore, according to the structure in which the thermal deformationportion 221 b is in contact with the lower surface of the base 11, it ispossible to easily connect the second impeller 2 to the first impeller1.

According to the above-described example embodiment of the presentdisclosure, the fixing portion 221 may have the claw 221 a. The claw 221a is hooked to the lower surface of the base 11.

Therefore, according to the structure in which the claw 221 a is hookedto the lower surface of the base 11, it is possible to easily connectthe second impeller 2 to the first impeller 1.

According to the above-described example embodiment of the presentdisclosure, the claw 221 a is provided on the axially lower side of theradially one end of at least one second blade 22.

Therefore, when the second impeller 2 is molded, it is possible toextract the metal mold in the axial direction.

According to the above-described example embodiment of the presentdisclosure, the claw 221 a is provided on the axially lower side of theradially inner end of at least one second blade 22.

Accordingly, compared to the case where the claw 221 a is provided onthe axially lower side of the radially outer end of the second blade 22,the claw 221 a does not easily interfere with other members when theimpeller 100 is assembled.

According to the above-described example embodiment of the presentdisclosure, the claw 221 a is located radially inside the radially innerperipheral edge 21 b of the shroud 21.

Accordingly, when the second impeller 2 is molded using the metal mold,it is possible to extract the metal mold in the axial direction.Thereby, the impeller 100 is easily manufactured.

According to the above-described example embodiment of the presentdisclosure, when viewed in the axial direction, the claw 221 a extendsfrom the radially inner end of at least one second blade 22 to thecentral axis CA side in the direction in which at least one second blade22 extends.

Accordingly, when the second impeller 2 is connected to the firstimpeller 1, the first blade 12 adjacent to at least one second blade 22does not easily come into contact with the claw 221 a.

According to the above-described example embodiment of the presentdisclosure, the upper surface of the claw 221 a is in contact with thelower surface of the base 11. The axially lower end of the second blade22 faces the bottom surface of the first groove 11 a with a gap betweenthe bottom surface of the first groove 11 a and the axially lower end ofthe second blade 22.

Accordingly, it is possible to easily hook the claw 221 a to the lowersurface of the base 11. In addition, it is possible to prevent a gapfrom being generated between the upper surface of the claw 221 a and thelower surface of the base 11. Therefore, it is possible to increaseconnection strength between the first impeller 1 and the second impeller2. In addition, it is possible to effectively suppress or preventoccurrence of a gap between the second blade 22 and the flange 112.

According to the above-described example embodiment of the presentdisclosure, the impeller 100 further includes the filler 3 providedinside the through-hole 11 b.

Accordingly, it is possible to prevent the air flowing between the firstblades 12 from leaking in the axial direction through the through-hole11 b.

According to the above-described example embodiment of the presentdisclosure, the filler 3 covers at least a portion of the claw 221 aoutside the through-hole 11 b.

Accordingly, at least a portion of the claw 221 a is able to be fixed tothe base 11 by the filler 3, and thus, it is possible to furtherincrease the connection strength between the first impeller 1 and thesecond impeller 2.

According to the above-described example embodiment of the presentdisclosure, the shroud 21 has the second groove 21 a which is recessedaxially upward. The second groove 21 a is provided between the secondblades 22 adjacent to each other and extends in the direction in whichat least one first blade 12 extends. The axially upper end of at leastone first blade 12 is located in the second groove 21 a.

Accordingly, even in a case where a gap is defined between at least onefirst blade 12 and the shroud 21, it is possible to prevent the air fromleaking from a portion between the first blade 12 and the shroud 21.Therefore, it is possible to suppress the decrease in efficiency whichthe air is sent to the radially outer side of the impeller 100 by atleast one first blade 12.

According to the above-described example embodiment of the presentdisclosure, the radially inner end of the second blade 22 is locatedradially outside the radially inner end of the first blade 12.

Accordingly, it is possible to prevent the gap between the radiallyinner ends of the first blades 12 from being too narrowed by the secondblade 22. Accordingly, a flow of the air flowing into a portion betweenthe first blades 12 is not able to be easily hindered by the secondblade 22.

According to the above-described example embodiment of the presentdisclosure, the radially inner end of the second blade 22 is locatedradially outside a radially outer end of the cup portion 111.

Accordingly, when the second impeller 2 is connected to the firstimpeller 1, it is possible prevent the second blades 22 from abutting onthe cup portion 111. Therefore, the connection operation of the firstimpeller 1 and the second impeller 2 is easily performed.

According to the above-described example embodiment of the presentdisclosure, when viewed in the axial direction, the length of the secondblade 22 along the direction in which the second blade 22 extends isshorter than the length of the first blade 12 along the direction inwhich the first blade 12 extends.

Accordingly, when the second impeller 2 is connected to the firstimpeller 1, the second blade 22 does not easily abut on the cup portion111. Therefore, a connection between the first impeller 1 and the secondimpeller 2 is easily performed.

For example, the example embodiment of the present disclosure is usefulfor an impeller of a blower which radially outward sends out the airtaken into the blower.

Features of the above-described example embodiments and themodifications thereof may be combined appropriately as long as noconflict arises.

While example embodiments of the present disclosure have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present disclosure. The scope of the presentdisclosure, therefore, is to be determined solely by the followingclaims.

1-17. (canceled) 18: An impeller rotatable about a central axisextending in an axial direction, the impeller comprising: a firstimpeller; and a second impeller connected to the first impeller; whereinthe first impeller includes: a base; and a plurality of first bladesarranged in a circumferential direction; the base includes: a cupportion including an axially upper end that is closed; and a flangeextending radially outward from an axially lower end of the cup portion;the second impeller includes: a shroud with an annular or substantiallyannular shape about the central axis and opposing an upper surface ofthe flange in an axial direction; and a plurality of second bladesarranged in the circumferential direction; each of the first bladesprotrudes axially upward from the flange; each of the second bladesprotrudes axially downward from the shroud; and in the circumferentialdirection, at least one second blade is located between the first bladesadjacent to each other. 19: The impeller according to claim 18, whereinthe base includes a first groove recessed axially downward; the firstgroove is between the first blades adjacent to each other and extends ina direction in which the at least one second blade extends; and anaxially lower end of the at least one second blade is located in thefirst groove. 20: The impeller according to claim 18, wherein the baseincludes a through-hole penetrating the base in the axial direction; theat least one second blade includes a fixing portion extending in theaxial direction; and the fixing portion is fixed to the base through thethrough-hole. 21: The impeller according to 20, wherein a fixing portionincludes a thermal deformation portion in which a portion of the fixingportion is thermally deformed; and the thermal deformation portion is incontact with a lower surface of the base. 22: The impeller according toclaim 20, wherein the fixing portion includes a claw; and the claw ishooked to a lower surface of the base. 23: The impeller according toclaim 22, wherein the claw is provided on an axially lower side of aradial end of the at least one second blade. 24: The impeller accordingto claim 23, wherein the claw is provided on an axially lower side of aradially inner end of the at least one second blade. 25: The impelleraccording to claim 23, wherein the claw is located radially inside of aradially inner peripheral edge of the shroud. 26: The impeller accordingto claim 25, wherein when viewed in the axial direction, the clawextends from the radially inner end of the at least one second blade tothe central axis side in a direction in which the at least one secondblade extends. 27: The impeller according to claim 19, wherein an uppersurface of the claw is in contact with the lower surface of the base;and the axially lower end of the second blade opposes a bottom surfaceof the first groove with a gap therebetween. 28: The impeller accordingto claim 23, wherein the impeller further includes a filler inside thethrough-hole. 29: The impeller according to claim 28, wherein the fillercovers at least a portion of the claw outside the through-hole. 30: Theimpeller according to claim 18, wherein the shroud includes a secondgroove recessed axially upward; the second groove is provided betweentwo of the second blades adjacent to each other and extends in adirection in which the at least one first blade extends; and an axiallyupper end of the at least one first blade is located in the secondgroove. 31: The impeller according to claim 18, wherein a radially innerend of the second blade is located radially outside a radially inner endof the first blade. 32: The impeller according to claim 18, wherein aradially inner end of the second blade is located radially outside aradially outer end of the cup portion. 33: The impeller according toclaim 18, wherein when viewed in the axial direction, a length of thesecond blade along a direction in which the second blade extends isshorter than a length of the first blade along a direction in which thefirst blade extends. 34: A blower comprising: the impeller according toclaim 18 that is rotatable about the central axis; and a motor to drivethe impeller.